Smart folders should sync automatically. Have you tried the “Synchronize now” command, others synchronization only runs every 5 minutes.
Preferences are not synched across all Macs.
No, you have to import auction not started from GarageSale using the “Import from My eBay” command. But once you have imported these auctions from eBay onto a synched Mac, they should appear on your other synched Mac. However, uploading and downloading 4000 listings though our sync server might take a while. You might want to check the state of the synching by looking at the “Synching” submenu in the “File” menu.
Running the “Import from My eBay” command on both Macs, while the synching is still not finished, will most likely cause duplicate auctions to appear on both of your Macs. I recommend not doing that.